The NCPA Emergency Communications Special Interest Group coordinates the use of Emergency frequencies. Frequency coordination is a valuable service which helps to insure that each device can reach the other devices it needs to, while not overloading any one channel. Frequency coordination also maximizes reuse of frequencies in a manner that minimizes interference with other users of the frequency.
The NCPA EP-SIG maintains a database of devices which are using the Emergency Digital Frequencies. The database includes information about each node such as call sign, emergency organization affiliation, location (lat/lon), antenna height, power, device type, etc. Terrain mapping radio propagation prediction software is then used to map the theoretical radio coverage of each device. This information, coupled with practical experience and other information is used to suggest frequencies for use by individual devices or groups of devices. In this way, emergency groups in neighboring areas can avoid over-subscribing a particular frequency.
The frequencies currently allocated to EP are shown on the NCPA digital band plan. Users of the EP frequencies agree to participate in frequency coordination. The steps involved depend largely on whether one needs to coordinate an individual node or a whole network of nodes. Generally, the steps are:
- Determine how many frequencies you will need for your application or network. Larger networks of devices may need more than one frequency.
- Review the NCPA band plan to understand which frequencies are allocated to emergency digital use
- Listen for other traffic on the frequencies and decide on which frequencies you think would be best for your application. In some cases, one may prefer a particular frequency because there is a minimum of traffic. In other cases, one may prefer a specific frequency because other devices that are important to the network are on that same frequency.
- Contact one of the frequency coordinators to discuss your needs and frequency plan. They may be able to share additional information and offer suggestions on frequency usage.
- The applicant will complete the EP-SIG Frequency Coordination Application (see below) and return it to an EP-SIG frequency coordinator.
- The coordinator will input your information into the database. Based on the information in the application, the coordinator may be able to provide coverage plots or other helpful information to the applicant or to existing packet devices which may be impacted by the proposed node. For systems in the 70cm band, the coordinator can also assist with determining if interference with PAVE PAWS at Beale AFB will be an issue.
- The coordinator will make a notice regarding the new application and solicit comments for a two week period.
- The coordinator will advise the applicant of any issues raised during the notice period. It is the applicant’s responsibility to resolve any issues. Whenever possible, the coordinator will provide assistance to the applicant in resolving any issues that may have been raised.
- At the end of the two week notice period, the coordinator will review any open issues with the applicant.
- If there are no unresolved issues, the coordinator will make notice of the new coordination and the applicant will be considered coordinated.
- If there are issues which cannot be resolved by the applicant, the issues will be brought to the NCPA EP-SIG for discussion and resolution.
Frequency Coordination Application
The following form provides the frequency coordinators the information they need to accurately plot coverage and interference issues:
EP-SIG Frequency Coordination Application (Rev 2010-04-12)
Frequency coordination duty is currently shared by two of the emergency digital special interest group representatives. Contact either one for help.
David Coursey n5fdl at arrl dot net
Michael Fox n6mef at arrl dot net